Magnetic random access memory (MRAM) utilizing magnetic flip-flop structures

Abstract

Non-volatile magnetic random access memory (MRAM) devices that include magnetic flip-flop structures that include a magnetization controlling structure; a first tunnel barrier structure; and a magnetization controllable structure that includes a first polarizing layer; and a first stabilizing layer, wherein the first tunnel barrier structure is between the magnetization controllable structure and the magnetization controlling structure and the first polarizing layer is between the first stabilizing layer and the first tunnel barrier structure, wherein the magnetic flip-flop device has two stable overall magnetic configurations, and wherein a first unipolar current applied to the device will cause the orientation of the magnetization controlling structure to reverse its orientation and a second unipolar current applied to the electronic device will cause the magnetization controllable structure to switch its magnetization so that the device reaches one of the two stable overall magnetic configurations, wherein the second unipolar current has an amplitude that is less than the first unipolar current; a second tunnel barrier structure and a reference layer, wherein the second tunnel barrier structure is between the magnetic flip-flop device and the reference layer. MRAM cells that include such devices and arrays including such cells are also disclosed.

1. A magnetic random access memory device comprising:
 a magnetic flip-flop structure comprising:
 i. a magnetization controlling structure; 
 ii. a first tunnel barrier structure; and 
 iii. a magnetization controllable structure comprising:
 a first polarizing layer; and 
 a first stabilizing layer, 
 
 
 wherein the first tunnel barrier structure is between the magnetization controlling structure and the magnetization controllable structure and the first polarizing layer is between the first stabilizing layer and the first tunnel barrier structure 
 wherein the magnetic flip-flop structure has two stable overall magnetic configurations, and 
 wherein a first unipolar current applied to the MRAM device will cause the orientation of the magnetization controlling structure to reverse its orientation and a second unipolar current applied to the MRAM device will cause the magnetization controllable structure to switch its magnetization so that the device reaches one of the two stable overall magnetic configurations, wherein the second unipolar current has an amplitude that is less than the first unipolar current; 
 a reference layer 
 a second tunnel barrier structure located between the reference layer and the magnetic flip-flop structure. 
 
     
     
       2. The magnetic random access memory device according to  claim 1 , wherein the magnetization controlling structure comprises a second polarizing layer and a second stabilizing layer. 
     
     
       3. The magnetic random access memory device according to  claim 2 , wherein the first and second stabilizing layers are independently chosen from the group consisting of: alloys of gadolinium (Gd), alloys of terbium (Tb), alloys of dysprosium (Dy), alloys of cobalt (Co) and alloys of samarium (Sm). 
     
     
       4. The magnetic random access memory device according to  claim 2 , wherein the first and second stabilizing layers are independently chosen from the group consisting of: GgTbCoFe, and TbCoFe. 
     
     
       5. The magnetic random access memory device according to  claim 2 , wherein the first stabilizing layer is chosen from the group consisting of: CoCrPt, CoPt, Co/Pt Co/Ni, Co/Cu and Co/Pd; and the second stabilizing layer comprises TbCoFe. 
     
     
       6. The magnetic random access memory device according to  claim 1 , wherein the magnetization controlling structure comprises an antiferromagnetic layer and a ferromagnetic layer exchange coupled to the antiferromagnetic layer. 
     
     
       7. The magnetic random access memory device according to  claim 1 , wherein the magnetization controlling structure has a first magnetic coercivity at room temperature and a second magnetic coercivity at an operating temperature of the electronic device and the magnetization controllable structure has a first magnetic coercivity at room temperature and a second magnetic coercivity at the operating temperature of the electronic device, and wherein the first magnetic coercivity of the magnetization controlling structure is higher than the first magnetic coercivity of the magnetization controllable structure and the second magnetic coercivity of the magnetization controlling structure is lower than the second magnetic coercivity of the magnetization controllable structure. 
     
     
       8. The magnetic random access memory device according to  claim 1 , wherein the first or second tunnel barrier structure comprises SiO x , SiN x , SiO x N y AlO x , TO x , TiO x  or AlN x . 
     
     
       9. The magnetic random access memory device according to  claim 1 , wherein the reference layer comprises cobalt (Co), iron (Fe), boron (B), nickel (Ni), manganese (Mn) or alloys thereof. 
     
     
       10. The magnetic random access memory device according to  claim 1  further comprising a seed layer and a cap layer. 
     
     
       11. The magnetic random access memory device according to  claim 10  further comprising a diode in electrical connection with the seed layer. 
     
     
       12. A magnetic random access memory (MRAM) cell comprising:
 a MRAM device comprising 
 a magnetic flip-flop device comprising:
 i. a magnetization controlling structure; 
 ii. a first tunnel barrier structure; and 
 iii. a magnetization controllable structure comprising:
 a first polarizing layer; and 
 a first stabilizing layer, 
 
 
 wherein the first tunnel barrier structure is between the magnetization controllable structure and the magnetization controlling structure and the first polarizing layer is between the first stabilizing layer and the first tunnel barrier structure, 
 wherein the electronic device has two stable overall magnetic configurations, and 
 wherein a first unipolar current applied to the electronic device will cause the orientation of the magnetization controlling structure to reverse its orientation and a second unipolar current applied to the electronic device will cause the magnetization controllable structure to switch its magnetization so that the device reaches one of the two stable overall magnetic configurations, wherein the second unipolar current has an amplitude that is less than the first unipolar current; 
 a reference layer; and 
 a second tunnel barrier structure 
 wherein the second tunnel barrier structure is between the magnetic flip-flop device and the reference layer; and 
 a diode, wherein the diode is electrically coupled to the MRAM device to control current flow. 
 
     
     
       13. The magnetic random access memory cell according to  claim 12  further comprising a first conductive element electrically coupled to the diode and a second conductive element electrically coupled to the magnetic flip flop device. 
     
     
       14. The magnetic random access memory cell according to  claim 12 , wherein the magnetic random access memory cell is configured in an array with a plurality of other magnetic random access memory cells. 
     
     
       15. The magnetic random access memory cell according to  claim 14 , wherein the array comprises select transistors used to select entire rows or columns of the array and not individual MRAM cells. 
     
     
       16. The magnetic random access memory cell according to  claim 14 , wherein the array is configured in a three dimensional structure with a plurality of other arrays comprising magnetic random access memory cells. 
     
     
       17. The magnetic random access memory cell according to  claim 16 , wherein the three dimensional structure comprises a bottom conductive column layer, a bottom diode layer, a bottom MRAM layer, a bottom conductive row layer, an array insulator layer, a top conductive column layer, a top diode layer, a top MRAM layer and a top conductive row layer. 
     
     
       18. The magnetic random access memory cell according to  claim 12 , wherein the diode comprises a thin film p-n diode comprising semiconductive oxide materials. 
     
     
       19. A method of accessing a memory array comprising:
 providing an array of unipolar MRAM cells, each cell serially connected to a diode, configured in rows and columns with row conductors and column conductors; 
 setting all row conductors to a high potential and setting all column conductors to a low potential; 
 accessing a desired MRAM cell by setting a corresponding desired column conductor to a high potential and setting a corresponding desired row conductor to a low potential; and 
 passing a unipolar current with a write current between about 30 and 100 microamperes to the desired MRAM cell. 
 
     
     
       20. A method of accessing a memory array comprising:
 providing an array of unipolar MRAM cells, each cell serially connected to a diode, configured in rows and columns with row conductors and column conductors; 
 setting all row conductors to a high potential and setting all column conductors to a low potential; 
 accessing a desired MRAM cell by setting a corresponding desired column conductor to a high potential and setting a corresponding desired row conductor to a low potential; and 
 passing a unipolar current with a read current between about 10 and 35 microamperes to the desired MRAM cell. 
 
     
     
       21. A magnetic random access memory device comprising:
 a magnetic flip-flop structure comprising:
 i. a magnetization controllable structure comprising:
 a first polarizing layer; and 
 a first stabilizing layer, 
 
 ii. a first tunnel barrier structure; and 
 iii. a magnetization controlling structure comprising:
 a second polarizing layer; and 
 a second stabilizing layer; 
 
 
 wherein the first tunnel barrier structure is between the magnetization controlling structure and the magnetization controllable structure and the first polarizing layer is between the first stabilizing layer and the first tunnel barrier structure 
 wherein the magnetic flip-flop structure has two stable overall magnetic configurations, and 
 wherein the first and second stabilizing layers are independently chosen from the group consisting of: alloys of gadolinium (Gd), alloys of terbium (Tb), alloys of dysprosium (Dy), alloys of cobalt (Co) and alloys of samarium (Sm); 
 a reference layer; and 
 a second tunnel barrier structure located between the reference layer and the magnetic flip-flop structure. 
 
     
     
       22. The magnetic random access memory device according to  claim 21 , wherein the first and second stabilizing layers are independently chosen from the group consisting of: GgTbCoFe, and TbCoFe. 
     
     
       23. The magnetic random access memory device according to  claim 21 , wherein the first stabilizing layer is chosen from the group consisting of: CoCrPt, CoPt, Co/Pt Co/Ni, Co/Cu and Co/Pd; and the second stabilizing layer comprises TbCoFe. 
     
     
       24. The magnetic random access memory device according to  claim 21 , wherein the first or second tunnel barrier structure comprises SiO x , SiN x , SiO x N y AlO x , TO x , TiO x  or AlN x . 
     
     
       25. The magnetic random access memory device according to  claim 21 , wherein the reference layer comprises cobalt (Co), iron (Fe), boron (B), nickel (Ni), manganese (Mn) or alloys thereof. 
     
     
       26. The magnetic random access memory device according to  claim 21  further comprising a seed layer and a cap layer.